The objective of this research and development program is to demonstrate the technical feasibility of detecting and monitoring isocyanates in workplace air at or below the Threshold Limit Value (TLV) 0.02 ppm using a real-time monitoring technique. The proposed instrument will detect and analyze for isocyanates in both vapor and aerosol form and will serve as a workplace monitor for isocyanates to replace the decertified colorimetric methods. The instrument development test work will include tests to verify the ability of the method to detect all major isocyanates in commercial use at or below the TLV. Tests will also demonstrate the ability of the method to discriminate among individual isocyanates and its's freedom from response to common interferents. Isocyanates exposure has been linked to occupational asthma as a major causative factor and thus the development of the proposed monitor will fill an occupational monitoring need of substantial importance.